The present invention is directed to a high density junction capacitor structure that is formed utilizing a single mask and a series of angled ion implants resulting in an inter-digitated capacitor with superior diode breakdown, forward resistance and capacitance density characteristics.
PN junctions are commonly used in semiconductor integrated circuits as diode-capacitor elements. The depletion layer of a PN junction is the interface of the junction and, as the name implies, is depleted of charge carriers. Under certain bias conditions, the depletion layer of a PN junction is capable of storing charge carriers. The capacitance of the depletion layer is proportional to its area. That is, for a given set of bias conditions, the greater the area occupied by the PN junction, the greater the capacitance. Of course, may integrated circuit applications require that the die size of the circuit be as small as possible. Therefore, it would be highly desirable to have available a PN junction capacitor structure that provides increased capacitance while utilizing smaller area.
A capacitor with an increased capacitance per unit area and for a given voltage range of operation is thus a valuable device. Capacitors with higher levels of doping offer a higher per unit area capacitance, but trade off breakdown voltage. Thus, a valuable device would offer both a high per unit area capacitance and a high breakdown voltage. A capacitor with a high breakdown voltage and a high per unit area capacitance is currently not readily available as a single PN junction.